This section starts on page 89 of "The Chemistry of Essential Oils Made Simple" by Dr. David Stewart. I got a tad bored with it, but I'm going to drive through in the hopes that it will get interesting again, and that it will help with referencing throughout the rest of the book.
Oxygen is the most abundant element and it makes up around 49% of the earth's crust, 21% of the atmosphere, 90% of the oceans' weight, 88% of plant mass, and 76% of body weight of people and animals.
Silicon is the second most abundant element and it makes up about 75% of the rocks and soils on the earth. It is usually found in the form of silicon dioxide, which crystalline quartz, sandstone, and normal sand are made of. Most beaches are made up of silica or silicon dioxide.
The third most abundant element is aluminum. It is the most abundant metal on the earth. It is in most igneous rocks and all clays. Current science says it has no role in biological processes. It is not found free in nature, which means it is bound up in stable compounds and is not released by itself.
Oxygen, Carbon, Nitrogen and Hydrogen make up over 90% of the weight in plants and animal bodies. Oxygen and Hydrogen are the most abundant out of these. The human body is also made up of less than .5% of these elements: Calcium, Phosphorus, Chlorine, Potassium, Sulfur, Sodium, and Magnesium. There is one Phosphorus atom in every nucleotide unit in our DNA, except the teeth and bones. 17 other elements are present in the body at less than .05%. Iron is one of these, and carries oxygen in the blood which makes it extremely important.
Essential oils are also made up of trace components that contribute to their therapeutic properties. Some are not even named yet. This is a huge reason why we have to be so careful in growing plants for essential oils and in processing them, because one mess-up will completely change the therapeutic status of an oil.
Galbanum is an example of an oil with a known trace component that is very important. The component is called pyrazine, and it's responsible for the strongly earthy smell of Galbanum, and contributes to its therapeutic properties. Galbanum is one of the oils in the recipe listed in Exodus 30:34 of the Bible.
Current science says that not all 92 elements are essential to life. Actually, only 27 are currently considered necessary to the human body. 95% of our weight comes from carbon, nitrogen and oxygen. These elements are numbers 6, 7, and 8 on the Table of Elements. It probably means nothing, but I thought it was cool that the number of man, the number of completion, and the number of new beginnings are that important to our life. Most atoms in the body are hydrogen atoms, but it's so light that it really doesn't make weight. The first 20 elements on the Table are considered necessary to the human body, except Beryllium and Aluminum. Beryllium is what makes emeralds green, but it's very toxic. You will like to know that it is never found free in nature.
Current science says that most of the heavier elements are actually toxic to us, like Mercury. Exceptions to this rule are Iodine and Molybdenum. They are considered the only elements with an atomic weight of over 79 that are currently considered usable by the human body.
Many essential oils chelate heavy metals out of the body, like Helichrysum and Cardamom, so they're nice to have around the house to help with cavity fillings and vaccinations and such.